Integrated electronic arrays are among the most important components in modern integrated electronics due to the wide number of functions which can be performed at an economic cost by such integrated arrays. In the crystalline semiconductor industry, the size of electronic arrays is limited to a fraction of the size of the single-crystal wafer with which crystalline semiconductor devices and circuits which form such arrays are fabricated. Although a crystalline silicon wafer upon which such arrays are fabricated may be between 3 and 8 inches in diameter, the entire wafer area cannot be used to fabricate just one or even a few very large integrated circuits or arrays, due to the well-known problem of defects in crystalline semiconductor devices, which reduces yields to zero percent as the size of the integrated circuit or array begins to approach a sizable function of the size of the crystalline wafer.
Thin film semiconductor material, devices and circuits which may be made using polycrystalline, microcrystalline or amorphous semiconductors or a combination thereof, do not have such inherent limitations. Such non-single-crystal semiconductor materials, like insulators and metals, are deposited as thin films by various techniques such as evaporation, sputtering or vapor deposition, and patterned to form many types of thin film integrated electronic devices, circuits, and arrays useful for a wide variety of applications. Thin film electronic structures may be fabricated over very large areas, making it possible to implement very large scale integration (VLSI) an ultra-large scale integration (ULSI) electronic circuitry, without the use of costly one micron or submicron geometries. Such circuits and arrays typically employ larger feature sizes, such as several microns to 20 microns or more, than do their single-crystal counterparts. Hence, thin films may be reliably deposited and patterned with greater ease and higher yields then their crystalline counterparts. The fabrication of thin film VLSI and ULSI circuits and arrays having large feature sizes is less expensive than the high resolution, high temperature processing which must be carried out in order to produce VLSI and ULSI electronic circuitry on crystalline wafers with acceptable yields.